1. Field of the Invention
This invention relates to means and methods for increasing coke quality and production capability of a non-by product recovery coke oven by compacting and thereby increasing the bulk density of a bed of coking coal introduced into the oven, and particularly to compaction of the coal by means of a vertically vibrating compactor attached to an end of a coal charging machine and is upwardly pivotable away from the compacted coal bed to allow finished coke to be pushed out of the coke oven.
2. Description of the Prior Art
An early type of coke oven was the so-called "bee hive" oven in which coal was coked without recovery of volatile by products ("non-recovery" coke ovens). By-product recovery coke ovens largely replaced early non-recovery ovens in order to recover the many valuable by-products of the coking process. However, improved designs of non-recovery coke ovens have seen a recent resurgence of interest and application of such ovens due to their low capital, operating and maintenance costs along with their ability to produce good quality coke.
A modern non-recovery coke oven is a refractory structure constructed of silica brick. It is used to convert coal into blast furnace grade coke by heating the coal in a reducing atmosphere (produced by off-gases and vapors from the coking process) and under a negative pressure (to reduce escape of evolved volatiles to the atmosphere). A recent non-recovery coke oven design, incorporating certain improvements by the present inventor, is shown in FIG. 1. After initial heating of the oven chamber, e.g. by a fuel-gas burner, a bed of coal is inserted into the oven through a removable oven charging door, e.g. by a coal charging machine. Such a machine of the prior art is shown in FIG. 2. It has several detriments. First, the conveyor is supported at one end adjacent the charging door and is cantilevered above the coal bed along the full length of the bed with the other end of the conveyor above the last portion of the bed to be deposited. With such construction, vertical deflection of the cantilevered conveyor results in a variation of the depth of the coal bed, with accompanying variation in heat transfer during coking and reduction of coke quality. Second, the coal falls from the conveyor only a small distance, e.g. about three feet, so that the deposited coal bed has a low bulk density.
Various means and methods have been developed in the prior art to increase the bulk density of coal beds introduced into coke ovens. For example, stamp charging of coal has long been used. In such technique, a plurality of drop hammers are caused to fall upon the top surface of the coal bed, thereby compacting the coal into a bed of increased density, which then is introduced into the coke oven. Stamp charging is exemplified in an article entitled Planning and Operation of a Stamp Charged Coke Oven Plant with Tall Ovens, by J. Echterhoff et al. describing a modern stamp charging facility installed at the Central Coke Oven Plant Saar, in the German Saar, in 1984.
U.S. Pat. Nos. 4,186,054 and 4,257,848 disclose compacting coal for coking by passing finely divided coal between opposed rotating rolls at a pressure of from about 20 to about 60 tons per linear inch.
In the non-coking area, it is known to pelletize finely divided coal for various uses of the carboniferous content, for example, as shown in U.S. Pat. No. 4,681,597. U.S. Pat. No. 5,658,357 describes the formation of coal "logs" by compacting coal fines with a binder in a mold or by extrusion to provide a safe and readily transportable form of coal, e.g. in an hydraulic pipeline.